Active pharmaceutical ingredients (APIs) can be prepared in a variety of different forms, for example, chemical derivatives, solvates, hydrates, co-crystals, or salts. APIs may also be amorphous, may have different crystalline polymorphs, or may exist in different solvation or hydration states. By varying the form of an API, it is possible to vary the physical properties thereof. For instance, crystalline polymorphs typically have different solubilities such that a more thermodynamically stable polymorph is less soluble than a less thermodynamically stable polymorph. Polymorphs can also differ in properties such as stability, bioavailability, morphology, vapor pressure, density, color, and compressibility. Accordingly, variation of the crystalline state of an API is one of many ways in which to modulate the physical and pharmacological properties thereof.
Various synthetic small organic molecules that are biologically active and generally known in the art as “fused pyrrolocarbazoles” have been prepared (See U.S. Pat. Nos. 5,475,110; 5,591,855; 5,594,009; 5,616,724; and 6,630,500). In addition, U.S. Pat. No. 5,705,511 discloses fused pyrrolocarbazole compounds which possess a variety of functional pharmacological activities. The fused pyrrolocarbazoles were disclosed to be used in a variety of ways, including: enhancing the function and/or survival of cells of neuronal lineage, either singularly or in combination with neurotrophic factor(s) and/or indolocarbazoles; enhancing trophic factor-induced activity; inhibition of protein kinase C (“PKC”) activity; inhibition of trk tyrosine kinase activity; inhibition of proliferation of a prostate cancer cell-line; inhibition of the cellular pathways involved in the inflammation process; and enhancement of the survival of neuronal cells at risk of dying.
A specific fused pyrrolocarbazole compound, having the chemical designation 11-isobutyl-2-methyl-8-(2-pyrimidinylamino)-2,5,6,11,12,13-hexahydro-4H-indazolo[5,4-a]pyrrolo[3,4-c]carbazol-4-one is a potent, orally-active TIE-2/VEGF-R inhibitor having anti-tumor and anti-angiogenic activity, and is represented by the following formula (I):

This Compound is referred to hereinafter as “Compound I”. U.S. Pat. No. 7,169,802 describes Compound I and utility thereof.
Different chemical or solid state forms of Compound I can have different melting points, solubilities or rates of dissolution; these physical properties, either alone or in combination, can affect bioavailability. The physical properties of the various chemical/solid state forms of Compound I can also affect other aspects of drug development, such as manufacturing, processing, and storage characteristics. In light of the potential benefits of alternative forms of APIs, a need exists to identify and prepare alternative forms of Compound I.